I can confirm the issue on the OnePlus One on the RC branch
I've dug into it fairly deeply and the Queue table in the SQLite database in /home/phablet/.local/share/com.mikeasoft.podbird/Databases/ gets wiped as soon as the app is closed
What's in the Podcasts table obviously persists because subscriptions are remembered between sessions
When the app is open and episodes have been added to the queue the Queue table in the SQLite db is populated properly, but that data is then lost once the app is closed or the phone rebooted
It makes it very frustrating to use it as a daily driver podcast player
There are several other features I'd judge desirable to add if there's a renewed drive on Podbird development
Happy to help with testing & debugging if I can